Trim parts often include a carrier or substrate which defines the shape of the trim part. The trim part itself is often made from a rigid thermoplastic material such as polypropylene (PP) or acrylonitrile butadiene stryrene (ABS). Other common materials include natural long fibers or short wooden fibers. In order to give the trim part an aesthetic appearance, the substrate or carrier is covered by a covering, which often includes a decorative skin made from leather or polyvinylchloride (PVC). In addition, the covering can include a foam layer or a knitted fabric situated between the decorative skin and a carrier.
For aesthetic reasons, the decorative skin or the entire covering includes stitch lines or seams. The seams are introduced into the covering such that they are visible from the side visible from the interior of a vehicle. After the seams have been introduced into the covering, the covering including the seams is attached to the substrate.
Several methods are known of attaching the coverings to the substrate. Often the covering is laminated onto a front side of the carrier. Other methods include welding the covering onto the carrier or forming the carrier onto the rear, non-visible side of the covering by injection molding. While the latter method prohibits the use of sensitive materials such as leather, the former methods do not solve the problem of locating the stitch lines exactly where the designer of the trim part intends them to be. Arranging the covering including the stitches on the carrier is a very tedious and time-consuming exercise. Even after the covering has been laminated onto the carrier, the seams may change their location due to failures in the lamination, which results in an aesthetically challenged trim part with loose-looking seams.
The prior art shows several of the above-mentioned trim parts. Documents JP 2011/206295 and US 2005/0103247 are cited by way of example.